By Matthias Williams and Lefteris Papadimas ATHENS (Reuters) - Greece's government is under intense pressure to deliver unpalatable concessions to international creditors to break a four-month debt deadlock and save the country from looming default that could tip it out of the euro zone. With no sign of a breakthrough on a cash-for-reform deal after Greek Prime Minister Alexis Tsipras met European leaders for talks in Brussels, here are three scenarios of how the crisis could unfold. PLAYING FOR TIME Greece and its creditors play for time with an interim deal after Tsipras makes some face-saving concessions but the two sides leave the most difficult issues such as debt relief, comprehensive reforms and a third bailout programme for later discussion.